. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 390 X. GUO ET AL The remaining dyads segregated into anaphase II around 30 min post-fertilization (Fii PB2 was released in the majority of the eggs by n post-fertilization (Fig. IE). The remaining 10 maternal chromatids became in- visible. Fusion of pronuclei was not observed. Maternal chromosomes reappeared as 10 duplicated dyads before mitosis I. At the same time, 10 paternal dyads also became visible. The first mitotic division occurred between 55 and 65 min post-fertilization. The development of a nor- mal diploid is sch
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 390 X. GUO ET AL The remaining dyads segregated into anaphase II around 30 min post-fertilization (Fii PB2 was released in the majority of the eggs by n post-fertilization (Fig. IE). The remaining 10 maternal chromatids became in- visible. Fusion of pronuclei was not observed. Maternal chromosomes reappeared as 10 duplicated dyads before mitosis I. At the same time, 10 paternal dyads also became visible. The first mitotic division occurred between 55 and 65 min post-fertilization. The development of a nor- mal diploid is schematically represented in Figure 2A. Chromosome segregation in the treated groups Tnpolar segregation. Although CB may effectively block the release of PB1 (Guo et ai. 1992), the presence of CB had no apparent inhibitory effects on the segregation and movement of chromosomes during meiosis I. In the CB-treated groups, events during the first 15 min after fertilization were the same as in the untreated controls. Maternal chromosomes went through meiosis I and di- vided into two groups of dyads, and the peripheral group also condensed and compacted as in the control groups (Fig. 1C). Differences in the pattern of chromosome segregation between the control and treated groups appeared between 15 and 20 min post-fertilization (10 min after CB treat- ment). In the treated eggs, the compacted group of dyads (ten) at the peripheral pole was not released as PB1 and started to dissociate, become individual dyads, and mi- grate back toward the remaining group of dyads. No polar body was released at 20 min post-fertilization when eggs in the control groups released FBI. In the majority of treated eggs at 20 min post-fertiliza- tion, the two groups of dyads were united in a single clus- ter. At 25-30 min post-fertilization, the twenty dyads (ten from each group) randomly partitioned into three groups; each group (with 6-7 dyads on the average) was distributed on one of three division planes
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
